How can I stop window drafts?

Hello, I put in replacement windows about 2 years ago. Although my old windows were really terrible, I am still getting a big draft from my new windows, in particular the double and triple window seat windows in my living room and bedrooms. What can I do to make sure the drafts are sealed?

Trish J.

Hi Trish. Window drafts can be frustrating, especially when trying to keep your heating and cooling costs under control.

One of the biggest culprits for air intrusion is a lack of insulation between the frames and the wood framing at the window openings. Place your hand over the trim at the window perimeters on a windy day … if you can feel air coming in, adding insulation may be the solution.

Remove the trim carefully as you'll want to reinstall it when the project is complete. If you see any gaps, either put batt insulation into the space or use a spray foam product as a filler. Spray foam normally works best as it will expand to fill all the nooks and crannies. However, be careful as too much can expand to the point where it is difficult to operate the windows. Nail the trim back into place, do a little caulking, and that should correct the problem.

If the drafts are coming in through the windows themselves or where the doubles and triples are joined, that is another issue. Air at the center of the units may be due to the top and bottom sash not locking together properly. Adjusting the locks for a tighter fit should solve the problem.

Drafts at the top of the top sash could be due to misaligned window trim that is creating small gaps. This can often be corrected by inspecting the outside of the window and ensuring all trim is in place and fitted tightly.

Unfortunately, a frequent cause of drafts in double and triple windows is also the most difficult to correct: the method used to join the windows at the factory. Some replacement window companies have not perfected that connection, and it can be a big problem if the windows are on a side of the house that receives a lot of wind.

If that is where your draft is coming from, I suggest contacting the window manufacturer. They should have a regional customer service rep that can come to your home to inspect the replacement windows. They may have additional trim parts that can be installed to rectify the problem. However, depending on the manufacturer, there's a possibility that you might always have a draft at those connections.